What brings the membrane potential to threshold?
Correct answer: A. Influx of sodium ions across the postsynaptic membrane
- A. Influx of sodium ions across the postsynaptic membrane
- B. Outflow of sodium ions across the postsynaptic membrane
- C. Outflow of calcium ions across the postsynaptic membrane
- D. Influx of potassium ions across the postsynaptic membrane
Explanation
When an excitatory neurotransmitter binds to its receptor on the postsynaptic neuron, it triggers an influx of sodium ions (Na+) across the postsynaptic membrane. This influx of positively charged ions depolarizes the membrane, bringing the membrane potential closer to threshold. If the membrane potential reaches threshold (typically around -55mV), an action potential is generated.
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Coordination depends on receptors, neurons, synapses and nerve impulses, with reflex actions traced through the reflex arc and the roles of major brain regions. Chemical coordination covers endocrine glands and hormones, including how hormones regulate growth, metabolism, reproduction and internal balance, unlike rapid nervous control.
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